In recent years, with the proliferation of so-called smartphones, Internet traffic of mobile terminals has been rapidly increasing, and the traffic offload technology for reducing the load on a mobile core network has become more and more important. Attention has centered particularly on a small-sized base station that supports a traffic offload function called LIPA (Local IP Access) or SIPTO (Selected IP Traffic Offload) (see PTL 1 and NPLs 1 and 2).
For example, according to NPL 1, 5.3 (Solution 2), OPM (Offload Processing Module) that has a NAT (Network Address Translation) function and a routing function is provided to a base station (eNB), and it is determined, based on a destination address or the like, which of a mobile core network and the NAT function uplink traffic should be routed to. This routing determination is made based on routing rules that are downloaded from a base station management system or the like, or preconfigured, and is not supposed to require particular processing of a mobile terminal. Moreover, PTL 2 describes a technology of offloading to the Internet via a femto AP (Access Point). Moreover, PTL 3 describes that a bearer dedicated for local breakout is established, whereby the destination of traffic from a mobile terminal is made to be the Internet.    [PTL 1] Japanese Patent Application Unexamined Publication No. 2011-135417    [PTL 2] Japanese Patent Application Unexamined Publication No. 2011-097567    [PTL 3] Japanese Patent Application Unexamined Publication No. 2012-504898    [NPL 1] 3GPP TR23.829 v10.0.0 (2011-03)    [NPL 2] 3GPP TS23.401 v10.0.0 (2010-06)